What is the difference between world cup race skis and race stock skis?

i'm a new USSA ski racer, and i didn't race on actual race skis last season. now that i'm looking for 2 or 3 pairs for the upcoming season, i know i need FIS approved skis, and it seems hard to find in the descriptions. If a ski is a "race stock ski" is it most likely FIS approved? anything else to add would be super helpful. i need it! thanks.